Originally Posted by
Mookiesurfs
They could and they would. Probably not runaway trim, imo. A more plausible scenario for trim related loss of control at altitude is a gradual failure of a system that causes the autopilot to trim unremarkably, like a gradual fuel imbalance, rollback, or something else. The AP will trim to the limit of its authority and then kick off, handing you a plane that is well out of trim. This really should be manageable at 29,000’ but can be tricky the closer you get to 41,000’.
We can’t rule out a catastrophic event at cruise yet, bomb or otherwise.
The trim system in the 737 is very obvious if not annoying when running. That includes when the autopilot trims. If in fact they ignored the spinning trim wheels and noise as soon as the autopilot moved the elevator to counter the incorrect trim input the trim brake would engage and stop the runaway.